In one embodiment, the present invention relates to semiconductor device manufacturing, and more particularly to a method of fabricating semiconductor nanowires on a surface of a semiconductor substrate in which the spatial placement of the semiconductor nanowires is controlled by using an oxygen reactive seed material. The present invention also provides semiconductor structures including semiconductor nanowires. In yet another embodiment, the present invention relates to patterning of a compound semiconductor substrate or other like substrate which is capable of forming a compound semiconductor alloy with an oxygen reactive element during a subsequent annealing step for providing a patterned substrate that can be used in various applications including, for example, in semiconductor device manufacturing, optoelectronic device manufacturing and solar cell device manufacturing.
A nanowire refers to a wire having a diameter from about 1 nm to about 1,000 nm. Implied in the use of the term “nanowire” is the assumption that the length of the nanowire is substantially greater than the diameter of the nanowire. Nanowires having a diameter at a low end of the range, i.e., a diameter from about 1 nm to about 100 nm, exhibit quantum mechanical properties, and are also called “quantum wires”. A nanowire may comprise a metallic material, a semiconductor material, or an insulator material. Both organic nanowires, e.g., deoxyribonucleic acid (DNA), and inorganic nanowires are known in the art.
The ratio of the length of a nanowire to the diameter of the nanowire is referred to as an aspect ratio. Typical aspect ratios for nanowires range from 10 to 1,000,000. As such, one dimension, i.e., the length, of a nanowire may be considered to be virtually infinite for practical purposes, while the diameter of the nanowire determines predominant physical and chemical characteristics of the nanowire. Quantum mechanical properties of nanowires due to the limited dimension of the nanowire in the plane perpendicular to the length of the nanowire have been observed in many types of nanowires.
Devices employing semiconductor nanowires have been proposed in the art. One of the challenges in the manufacture of semiconductor devices employing semiconductor nanowires has been the difficulty in the patterning of the nanowires.
There are many known techniques for patterning semiconductor nanowires some of which are discussed in the publication to Hong J. Fan et al. entitled “Semiconductor Nanowires: From Self-Organization to Patterned Growth” Small 2006, 2, No. 6, 700-717. The techniques disclosed in the aforementioned publication employ materials which do not easily react with oxygen in templating the growth of the nanowires. Moreover, many of the materials discussed in the above publication like gold (Au) have detrimental effects on the electrical and/or optical characteristics of the nanowires that are grown.
It has been proven difficult to grow semiconductor nanowires with materials that are more compatible like aluminum (Al). The main difficulty is attributed to the fact that these materials react with oxygen which suppresses their ability to seed the growth of nanowires.